Kaganowicz, in a copending application, entitled "METHOD FOR PREPARING AN ABRASIVE COATING", Ser. No. 963,819, filed Nov. 27, 1978, discloses a method for preparing an abrasive silicon oxide coating on a substrate which includes subjecting to a glow discharge silane and a gaseous, oxygen-containing compound selected from the group consisting of N.sub.2 O, H.sub.2 O and CO.sub.2. The resulting silicon oxide coatings are abrasive enough to be employed in lapping hard materials such as diamond. However, an improved coating having increased abrasiveness which would decrease the time to lap an article would be useful for high volume production.